Integral rocket-ramjet with combustor plenum chamber

ABSTRACT

An integral rocket-ramjet engine, wherein a rocket fuel grain is located in the ramjet combustor, having a flow distribution plate forming a plenum chamber at the forward end of the engine to increase efficiency and stabilize the burning of the fuel during ramjet operation.

[111 3,802,192 Apr. 9, 11974 R555 46 6 &99 33 3 O0 66 O Mr by re mm wm a mhmm FCKS 782 6546 9999 wmmm INTEGRAL ROCKET-RAMJET WITH 2 987 875 COMBUSTOR PLENUM CHAMBER [75] Inventor: Edward T. Curran, Dayton, Ohio 3: 7:3 [73] The United States of America as Assignee:

represented by the Secretary of the United states Force, Primary ExaminerSamuel Feinberg Washington, DC.

[22] Filed: Oct. 4, 1972 [21] Appl. No.: 294,035

ABSTRACT An integral rocket-ramjet engine, wherein a rocket fuel grain is located in the ramjet combustor, having a flow distribution plate formin g a plenum chamber at e to increase efficienc and stabilize the burning of the fuel during ra operation.

mm my k Wm F 5 4" 2" 0 m u St Um 1 55 [58] Field of Search 60/225, 244, 245, 270,

the forward end of the engin y mjet References Cited UNITED STATES PATENTS 6 Drawing Figures 4 Claims,

Smith.......

PATENTED APR 9 I974 3 MN W mm Iv w mrv J\ TV M \WSKQQW qkvumoq a m v 0 Q9 mw ov 3 NM v wn wm mm m wm ww +w w H IF. PM mw 9m 9w PMENIED APR 9 I974 SHEET 2 (IF 4 QQQubQR PATENTEDAFR 91974' SHEET 3 EF 4 wumalmlmlmn PNENTEDAPR 91914 SHEET u or 4 INTEGRAL ROCKET-RAMJET WITH COMBUSTOR PLENUM CHAMBER BACKGROUND OF THE INVENTION There is a problem of maintaining a flame in high velocity streams such as in ramjet engines. In conventional ramjet engines, flameholders are provided to help overcome this problem.

In combustors designed for integral rocket-ram jet engines, the chamber has to contain the rocket boost fuel grain and conventional flameholders cannot be used to stabilize the combustion process. It is current practice in integral rocket-ramjet engines to simply dump the airflow into the combustor with no flame holding devices used.

BRIEF SUMMARY OF THE INVENTION According to this invention, a plenum chamber is provided at the head end of the combustor to control the distribution of the air and fuel flow into the combustion chamber so thatgood combustion and adequate cooling are obtained with minimum loss of boost propellant volume. This also permits the matching of the fuel injector elements with corresponding air passages. Flow distribution vanes and flow distribution and control devices can be provided in the plenum chamber.

IN THE DRAWINGS FIG. 1 is a partially cutaway schematic diagram of a prior art integral rocket-ramjet missile.

FIG. 2 shows the device of FIG. 1 after rocket .burnout.

FIG. 3 is a partially cutaway schematic view, partially in section, of an integral rocket-ramjet missile according to the invention.

FIG. 4 shows the device of FIG. 3 after rocket burnout.

FIG. 5 is a front end view of the device of FIG. 3.

FIG. 6 shows a cutaway view of the device of FIG. 4 with a modified flow distribution burner plate.

FIG. 7 is a sectional view of the device of FIG. 6 along the line 77.

FIG. 8 shows another modification of the device of FIG. 4.

FIG. 9 shows a modified fuel supply for the device of FIG. 4.

FIG. 10 shows a further modification of the flow distribution burner plate of the device of FIG. 4.

FIG. 11 shows a flow control system for the device of FIG. 4.

FIG. 12 is a section view of the device of FIG. 11 along the line 12-l2.

FIG. 13 shows a modified plenum chamber for the device of FIG. 4. FIG. 14 is a front end view of the device of FIG. 13.

FIG. 15 shows another modification of the plenum chamber of the device of FIG. 13.

FIG. I6 shows a modified air inlet and flow control for the device of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION Reference is now made to FIGS. 1 and 2 of the drawing, which show a prior art integral rocket-ramjet system wherein a rocket-boost fuel grain 22 is positioned within the combustor 24 for a ramjet. A conventional two-throat nozzle 26 is connected to the combus tor. Normally an insert 28 is located within the ramjet nozzle 29 and is released by means of explosive bolts 30 thus leaving the nozzle configuration for normal ramjet operation, as shown in FIG. 2. The pay load, ramjet fuel supply and fuel and rocket control systems are located in the missile body 32. When the rocket grain has burned out, the insert 28 is ejected and plug 34 is blown out by ram air in air inlet 36. Fuel is then supplied through a nozzle 38 for ramjet operation. Ignition is normally accomplished by meansof a pyrophoric material admitted through a nozzle, such as at 39.

According to this invention, a plenum chamber is provided within the ramjet combustor housing so that inlet flow is decoupled from the combustor flow which permits air and fuel flow patterns to be controlled with little dependence on intake operation.

In the devices of FIGS. 3-16, parts which are substantially the same as in the prior art devices of FIGS. land 2 are given like reference numbers.

In the device of FIGS. 3 and 4, the plenum chamber is formed by means of a flow distribution burner plate 40 positioned within the combustion chamber 24. A seal 42, which may be a serrated glass plate, may be placed between the plate 40 and the fuel grain 22' to cover holes 41. The seal 42 will be ejected by ram air after burnout of the fuel grain 22. The seal 42 could be shattered by an explosive charge or a spring loaded striker when needed. After rocket burnout, ramjet fuel is supplied to the combustion chamber through nozzles 38. The ramjet operation may be started as inprior art devices, such as by means of a pyrophoric material from nozzle 39. Air holes 43, around the periphery of wall plate 40, can provide air cooling to reduce wall temperature.

While the axial holes 41 are used in the plate 40 in the device of FIGS. 3 and 4, a very efficient distribution burner plate tested is shown in FIGS. 6 and 7. In this device, the holes 43 are inclined to the plane of the burner plate to provide a swirl within the combustion chamber which will provide more efficient mixing of the fuel and air.

Also, improved mixing may be achieved by having the edge of the plate 40" bent forward into a shape somewhat similar to a frustum of a cone.

By locating fuel injector nozzles 47 adjacent the burner plate 40, as in FIG. 9, the fuel injector elements may be matched to the corresponding air flow holes for greater stability and efficiency.

Where the injector nozzles are located adjacent the air holes, the plate 40" may be constructed with a projection 48 which would extend into fuel grain 22', as in FIG. 10. After rocket grain burnout, radial flow of fuel and air from holes 41 and nozzles 47 can be provided with this device.

The flow through the holes in a plate, such as shown in FIGS. 3 and 4, may be controlled by means of a rotating member 50 as shown in FIGS. 11 and 12. Rotation of the member 50 to cover and uncover the holes 41 in plate 40 may be accomplished by means of a high temperature solenoid 54 located adjacent the wall of the combustion chamber in the cooler air flow.

While the devices thus far described have the plenum chamber formed by closing off the head end of the combustion chamber, an annular plenum chamber may also be provided, as shown in FIGS. 13 and 14.

In the device of FIG. 13, inlets 36 dump air into an annular plenum chamber 55 external to the combustor 24. The wall 57 has openings 58 leading into the combustor 24, for a fuel and air mixture. Air passages 60 are also provided in the wall 57. Fuel is supplied to noz zles 62 through line 64 and annular supply line 65.

In the device of FIG. 15, the annular plenum chamber 55' is located within the combustor 24. In this device, fuel is supplied to axial nozzles 68 from an annular fuel supply line 69 and to radial nozzles 71 from an annular fuel supply line 72. Fuel and air holes 58 and air passages 60 are provided in walls 77 and 78 of the ple' nurn chamber 55'.

In the device of FIG. 16, air from a modified inlet 36" is directed by flow distributers 80 toward the flow distribution plate 40. Except for the use of flow distributers 80, the device operates as the device of FIGS. 3 and 4.

There is thus provided an integral rocket-ramjet engine which provides increased efficiency and a more stable burning of the fuel than prior art integral rocketramjet engines.

vI claim:

1. In an integral rocket-ramjet booster having a rocket housing; a payload within said housing; a ramjet combustor within said housing; means for supplying ram air to said ramjet combustor; means for supplying fuel to said ramjet combustor; a rocket fuel grain in the ramjet combustor and nozzle means connected to said ramjet combustor; an apparatus for stabilizing the burning of the fuel in the ramjet combustor after rocket burnout; comprising: means, adjacent the front end of the fuel grain, for forming a plenum chamber at the head end of said ram jet combustor for receiving ram air and fuel means, in said plenum chamber forming means, for providing a stabilized flow of air and fuel in the ramjet combustor; said means for forming a plenum chamber comprising a wall member spaced from the forward end of said combustor; said wall member having a plurality of passages for fuel and air; said wall member having a projection adapted to fit into a central cavity in said fuel grain; said projection including means for providing a radial flow of air and fuel into said combustor.

2. In an integral rocket-ramjet booster having a rocket housing; a payload within said housing; a ramjet combustor within said housing; means for supplying ram air to said ramjet combustor; means for supplying fuel to said ramjet combustor; a rocket fuel grain in the ramjet combustor and nozzle means connected to said ramjet combustor; an apparatus for stabilizing the burning of the fuel in the ramjet combustor after rocket burnout; comprising: means, adjacent the front end of the fuel grain, for forming a plenum chamber at the head end of said ramjet combustor for receiving ram air and fuel and means, in said plenum chamber forming means, for providing a stabilized flow of air and fuel in the ram jet combustor; said means for forming a plenum chamber comprising a wall member spaced from the forward end of said combustor; said wall member having a plurality of passages for fuel and air; means positioned adjacent and supported by said wall member for controlling the flow of fuel and air through said passages. l

3. In an integral rocket-ramjet booster having a rocket housing; a payload within said housing; a ramjet combustor within said housing; means for supplying ram air to said ramjet combustor; means for supplying fuel to said ramjet combustor; a rocket fuel grain in the ramjet combustor and nozzle means connected to said ramjet combustor; an apparatus for stabilizing the burning of the fuel in the ramjet combustor after rocket burnout; comprising: means, adjacent the front end of the fuel grain, for forming a plenum chamber at the head end of said ramjet combustor for receiving ram air and fuel and means, in said plenum chamber forming means, for providing a stabilized flow of air and fuel in the ramjet combustor; wherein the means for forming a plenum chamber includes means for providing a swirl of air and fuel in said combustor. v

4. In an integral rocket-ramjet booster having a rocket housing; a payload within said housing; a ramjet combustor within said housing; means for supplying ram air to said ramjet combustor; means for supplying fuel to said ram jet combustor; a rocket fuel grain in the ramjet combustor and nozzle means connected to said ramjet combustor; an apparatus for stabilizing the burning of the fuel in the ramjet combustor after rocket burnout; comprising: means, adjacent the front end of the fuel grain, for forming a plenum chamber at the head end of said ramjet combustor for receiving ram air and fuel and means, in said plenum chamber forming 'means, for providing a stabilizer flow of air and fuel in the ram jet combustor; said plenum chamber is an annular plenum chamber; means for providing a radial inward flow of air and fuel from said plenum chamber into the combustor. 

1. In an integral rocket-ramjet booster having a rocket housing; a payload within said housing; a ramjet combustor within said housing; means for supplying ram air to said ramjet combustor; means for supplying fuel to said ramjet combustor; a rocket fuel grain in the ramjet combustor and nozzle means connected to said ramjet combustor; an apparatus for stabilizing the burning of the fuel in the ramjet combustor after rocket burnout; comprising: means, adjacent the front end of the fuel grain, for forming a plenum chamber at the head end of said ramjet combustor for receiving ram air and fuel means, in said plenum chamber forming means, for providing a stabilized flow of air and fuel in the ramjet combustor; said means for forming a plenum chamber comprising a wall member spaced from the forward end of said combustor; said wall member having a plurality of passages for fuel and air; said wall member having a projection adapted to fit into a central cavity in said fuel grain; said projection including means for providing a radial flow of air and fuel into said combustor.
 2. In an integral rocket-ramjet booster having a rocket housing; a payload within said housing; a ramjet combustor within said housing; means for supplying ram air to said ramjet combustor; means for supplying fuel to said ramjet combustor; a rocket fuel grain in the ramjet combustor and nozzle means connected to said ramjet combustor; an apparatus for stabilizing the burning of the fuel in the ramjet combustor after rocket burnout; comprising: means, adjacent the front end of the fuel grain, for forming a plenum chamber at the head end of said ramjet combustor for receiving ram air and fuel and means, in said plenum chamber forming means, for providing a stabilized flow of air and fuel in the ramjet combustor; said means for forming a plenum chamber comprising a wall member spaced from the forward end of said combustor; said wall member having a plurality of passages for fuel and air; means positioned adjacent and supported by said wall member for controlling the flow of fuel and air through said passages.
 3. In an integral rocket-ramjet booster having a rocket housing; a payload within said housing; a ramjet combustor within said housing; means for supplying ram air to said ramjet combustor; means for supplying fuel to said ramjet combustor; a rocket fuel grain in the ramjet combustor and nozzle means connected to said ramjet combustor; an apparatus for stabilizing the burning of the fuel in the ramjet combustor after rocket burnout; comprising: means, adjacent the front end of the fuel grain, for forming a plenum chamber at the head end of said ramjet combustor for receiving ram air and fuel and means, in said plenum chamber forming means, for providing a stabilized flow of air and fuel in the ramjet combustor; wherein the means for forming a plenum chamber includes means for providing a swirl of air and fuel in said combustor.
 4. In an integral rocket-ramjet booster having a rocket housing; a payload within said housing; a ramjet combustor within said housing; means for supplying ram air to said ramjet combustor; means for supplying fuel to said ramjet combustor; a rocket fuel grain in the ramjet combustor and nozzle means connected to said ramjet combustor; an apparatus for stabilizing the burning of the fuel in the ramjet combustor after rocket burnout; comprising: means, adjacent the front end of the fuel grain, for forming a plenum chamber at the head end of said ramjet combustor for receiving ram air and fuel and means, in said plenum chamber forming means, for providing a stabilizer flow of air and fuel in the ramjet combustor; said plenum chamber is an annular plenum chamber; means for providing a radial inward flow of air and fuel from said plenum chamber into the combustor. 